Coiled tubing percussion drilling

ABSTRACT

A method of drilling a subterranean wellbore can include extending coiled tubing into the wellbore, and actuating an impact tool interconnected to the coiled tubing, thereby delivering impacts to a drill bit. A coiled tubing drilling system for drilling a subterranean wellbore can include coiled tubing, a drill bit, and an impact tool which delivers impacts to the drill bit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 USC §119 of the filing dateof International Application Serial No. PCT/US10/28570, filed Mar. 25,2010. The entire disclosure of this prior application is incorporatedherein by this reference.

BACKGROUND

The present disclosure relates generally to equipment utilized andoperations performed in conjunction with a subterranean well and, in anembodiment described herein, more particularly provides for coiledtubing percussion drilling.

Percussion drilling has been used in the past in conjunction withsegmented drill pipe, which has sufficient strength to absorb shocksproduced by percussion drilling. Coiled tubing has been used in the pastfor drilling with a drill bit rotated by a positive displacement motor.

However, certain benefits could be achieved if percussion drilling couldbe used in conjunction with coiled tubing. Therefore, it will beappreciated that improvements are needed in the arts of coiled tubingdrilling and percussion drilling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic partially cross-sectional view of a coiled tubingdrilling system and method which embody principles of the presentdisclosure.

FIG. 2 is a schematic elevational view of a bottom hole assembly whichmay be used in the system and method of FIG. 1.

FIG. 3 is a schematic elevational view of another configuration of thebottom hole assembly.

DETAILED DESCRIPTION

Representatively illustrated in FIG. 1 is a coiled tubing drillingsystem 10 and associated method which embody principles of the presentdisclosure. In the system 10 and method, coiled tubing 12 is used todrill a wellbore 14.

The coiled tubing 12 is stored on a spool or reel 16 (e.g., by beingwrapped about the reel). A tube guide 18 guides the coiled tubing 12into an injector 20, which is used to convey the coiled tubing into andout of the wellbore 14.

The coiled tubing 12 extends through a blowout preventer stack 22connected to a wellhead 24 for pressure control. Although a land-basedcoiled tubing rig is depicted in FIG. 1, coiled tubing can be deployedfrom floating rigs, jackups, platforms, subsea wellheads, or any otherwell location.

Fluid communication with the interior of the coiled tubing 12 isprovided via a conduit 26 secured to the reel 16. In various examplesdescribed herein, fluids such as air 28, water 30, oil 32, lubricant 34,friction reducer 36, natural gas 37, mist 38, foam 40, surfactant 42,nitrogen 44, various gases 46, drilling mud 47, etc., or any combinationthereof, may be flowed through the coiled tubing 12 during a drillingoperation.

Natural gas 37 is not currently preferred for use as the fluid, sincerelatively large amounts of this flammable gas would be needed to fillthe coiled tubing 12. Thus, the possible safety hazards may outweigh anyeconomic benefits of using natural gas 37.

The nitrogen 44 may have any purity. For example, 95% purity nitrogen or99.5 to 99.9% purity nitrogen may be used. The nitrogen 44 may beproduced and/or delivered to a wellsite by any method.

The nitrogen 44 may be produced on site (e.g., by a membrane separationprocess), or the nitrogen could be produced off site and delivered tothe well location via piping or pressurized containers. The nitrogen 44may be produced cryogenically. Preferably, any gas 46 (such as nitrogen44) used in the drilling operation is substantially free of oxygen, tothereby minimize corrosion of the coiled tubing 12.

At a lower end of the coiled tubing 12, a bottom hole assembly 48 isprovided for performing various functions in the drilling operation. Ofcourse, the main function performed by the bottom hole assembly 48 iscutting or drilling into the earth, in order to elongate the wellbore14.

For this purpose, the bottom hole assembly 48 includes a drill bit 50 atits lower end. The drill bit 50 may be any type of drill bit, but ispreferably designed specifically for percussion drilling (i.e., whereinimpacts are repeatedly delivered to the drill bit for cutting into theearth).

Connected above the drill bit 50 is an impact tool 52 which delivers theimpacts to the drill bit. Various types of impact tools may be used(e.g., pneumatic, hydraulic, electrical, magnetic, etc.).

The impacts may be delivered axially and/or torsionally to the drill bit50. An impact tool which may be used in the system 10 is the TORKBUSTER™marketed by Ulterra of Fort Worth, Tex. USA. Impact tools are alsodescribed in U.S. Pat. Nos. 6,742,609, 6,659,202, 5,396,965 and7,424,922, the entire disclosures of which are incorporated herein bythis reference.

The bottom hole assembly 48 can also include a variety of othercomponents, such as measurement while drilling sensors, logging whiledrilling sensors, directional drilling equipment, weights, reamers,motors, shock absorbers, etc. A few of these are described more fullybelow, but it should be clearly understood that the bottom hole assembly48 can comprise any number and combination of components, in keepingwith the principles of this disclosure.

Referring additionally now to FIG. 2, an example of a configuration ofthe bottom hole assembly 48, apart from the remainder of the system 10,is schematically illustrated. In this example, the bottom hole assembly48 includes a shock absorber 54 and one or more weights 56 (e.g., drillcollars) connected to the coiled tubing 12.

The impact tool depicted in FIG. 2 is a pneumatic hammer 52 a of thetype which generates impacts in response to flow of gas 46 or othercompressible fluids (such as air 28, natural gas 37, foam 40, nitrogen44, etc., and/or combinations thereof). The pneumatic hammer 52 a maydeliver the impacts to the drill bit 50 at regular periodic intervals,the impacts may be delivered at irregular intervals, or the impacts maybe delivered only when desired, etc.

Note that, in other examples, the pneumatic hammer 52 a (or any othertype of impact tool 52) could be combined with any of the othercomponents of the bottom hole assembly 48. For example, the impact tool52 could be combined with the drill bit 50 (e.g., as in the JACKBIT™marketed by NovaDrill of Provo, Utah USA), the shock absorber 54 and/orthe weight 56.

The shock absorber 54 mitigates the transfer of shock and vibration fromthe impact tool 52 to the coiled tubing 12. This aids in preventingfatigue damage to the coiled tubing 12 due to the operation of theimpact tool 52.

The weight 56 aids the drilling operation by providing a downwardlybiasing force to the drill bit 50, and by providing an inertial massagainst which the impact delivered by the impact tool 52 can react. Thepresence of this inertial mass also aids in mitigating fatigue damage tothe coiled tubing 12.

In the configuration of FIG. 2, the drill bit 50 may not rotate whilethe impacts are delivered from the impact tool 52 to the drill bit, andwhile the drill bit is cutting into the earth in the drilling operation.Thus, this example does not include any downhole means for rotating thedrill bit 50 (although the impact tool 52 may cause rotation of thedrill bit). However, other examples can incorporate rotation of thedrill bit 50 into the drilling operation.

Referring additionally now to FIG. 3, another configuration of thebottom hole assembly 48 is representatively illustrated. In thisconfiguration, the drill bit 50 is rotated while the impacts aredelivered by the impact tool 52, and while the drill bit cuts into theearth.

As depicted in FIG. 3, a positive displacement motor or drilling turbine58 is interconnected in the bottom hole assembly 48 above the impacttool 52. Positive displacement motors are also known to those skilled inthe art as Moineau-type motors, progressive cavity motors and mudmotors.

Positive displacement motors and drilling turbines produce rotation inresponse to flow of fluid through the motors and turbines. Examples ofpositive displacement motors and drilling turbines are described in U.S.Pat. Nos. 6,742,609, 7,416,034, 6,883,622, 6,527,513, 7,500,787,7,303,007 and 6,827,160, the entire disclosures of which areincorporated herein by this reference.

Preferably, a substantially incompressible fluid (or combination offluids) is flowed through the motor or turbine 58 to rotate the drillbit 50. The incompressible fluid(s) could be, for example, water 30, oil32, lubricant 34, friction reducer 36 and/or drilling mud 47.

The impact tool depicted in FIG. 3 is a fluid hammer 52 b of the typewhich generates impacts in response to flow of the incompressiblefluid(s) through the fluid hammer. The fluid hammer 52 b may deliver theimpacts to the drill bit 50 at regular periodic intervals, or theimpacts may be delivered at irregular intervals, only when desired, etc.

Thus, the flow of the incompressible fluid(s) can be used for operationof the fluid hammer 52 b, as well as for operation of the motor orturbine 58. However, it should be clearly understood that it is notnecessary for an impact tool used in combination with the motor orturbine 58 to generate impacts in response to flow of incompressiblefluid, since other types of impact tools (such as those which generateimpacts electrically, magnetically, etc.) could be used, in keeping withthe principles of this disclosure.

It may now be fully appreciated that several advancements are providedto the arts of percussion drilling and coiled tubing drilling by theabove disclosure. The system 10 and method described above provide foran overall increased rate of penetration in the drilling operation (inpart because connections typically do not need to be made in a coiledtubing string as a wellbore is being drilled, and percussion drilling ishighly effective in harder rock formations), fluid-sensitive formationscan be drilled using air 28, natural gas 37, nitrogen 44, other gases46, etc., with the configuration of FIG. 2, whereas substantiallyincompressible fluids can be used with the configuration of FIG. 3.

In particular, the above disclosure provides to the art a method ofdrilling a subterranean wellbore 14. The method includes extendingcoiled tubing 12 into the wellbore 14, and actuating an impact tool 52interconnected to the coiled tubing 12, thereby delivering impacts to adrill bit 50.

The impact tool 52 may comprise a fluid hammer 52 b or a pneumatichammer 52 a.

The method can include interconnecting a shock absorber 54 between thecoiled tubing 12 and the impact tool 52.

Actuating the impact tool 52 may include pumping a liquid (such as water30, oil 32, lubricant 34, friction reducer 36, surfactant 42, drillingmud 47, etc.) through the coiled tubing 12 to the impact tool 52.

Actuating the impact tool 52 may include pumping a gas 46 (such as air28, natural gas 37, nitrogen 44, etc.) through the coiled tubing 12 tothe impact tool 52.

The gas 46 may comprise nitrogen 44. Preferably, the gas 46 issubstantially free of oxygen.

Actuating the impact tool 52 can include pumping, along with the gas 46,additional one or more components selected from a lubricant 34, afriction reducer 36, a foam 40, oil 32, mist 38, drilling mud 47, andwater 30.

The method may include rotating the drill bit 50 while actuating theimpact tool 52. Rotating the drill bit 50 can include operating apositive displacement motor or turbine 58 which rotates the drill bit 50in response to fluid flow through the coiled tubing 12.

Actuating the impact tool 52 may be performed while the drill bit 50 isnot rotated.

Actuating the impact tool 52 can include pumping a compressible fluid(such as air 28, natural gas 37, foam 40, nitrogen 44, other gases 46,etc.) through the coiled tubing 12 to the impact tool 52.

Actuating the impact tool 52 can include pumping an incompressible fluid(such as water 30, oil 32, lubricant 34, friction reducer 36, drillingmud 47, etc.) through the coiled tubing 12 to the impact tool 52.

Also described by the above disclosure is a coiled tubing drillingsystem 10 for drilling a subterranean wellbore 14. The system 10 caninclude coiled tubing 12, a drill bit 50, and an impact tool 52 whichdelivers impacts to the drill bit 50.

It is to be understood that the various embodiments of the presentdisclosure described herein may be utilized in various orientations,such as inclined, inverted, horizontal, vertical, etc., and in variousconfigurations, without departing from the principles of the presentdisclosure. The embodiments are described merely as examples of usefulapplications of the principles of the disclosure, which is not limitedto any specific details of these embodiments.

In the above description of the representative embodiments of thedisclosure, directional terms, such as “above,” “below,” “upper,”“lower,” etc., are used for convenience in referring to the accompanyingdrawings. In general, “above,” “upper,” “upward” and similar terms referto a direction toward the earth's surface along a wellbore, and “below,”“lower,” “downward” and similar terms refer to a direction away from theearth's surface along the wellbore.

Of course, a person skilled in the art would, upon a carefulconsideration of the above description of representative embodiments ofthe disclosure, readily appreciate that many modifications, additions,substitutions, deletions, and other changes may be made to the specificembodiments, and such changes are contemplated by the principles of thepresent disclosure. Accordingly, the foregoing detailed description isto be clearly understood as being given by way of illustration andexample only, the spirit and scope of the present invention beinglimited solely by the appended claims and their equivalents.

1. A method of drilling a subterranean wellbore, the method comprising:extending coiled tubing into the wellbore; and actuating an impact toolinterconnected to the coiled tubing, thereby delivering impacts to adrill bit.
 2. The method of claim 1, wherein the impact tool comprises afluid hammer.
 3. The method of claim 1, wherein the impact toolcomprises a pneumatic hammer.
 4. The method of claim 1, furthercomprising interconnecting a shock absorber between the coiled tubingand the impact tool.
 5. The method of claim 1, wherein actuating theimpact tool further comprises pumping a liquid through the coiled tubingto the impact tool.
 6. The method of claim 1, wherein actuating theimpact tool further comprises pumping a gas through the coiled tubing tothe impact tool.
 7. The method of claim 6, wherein the gas comprisesnitrogen.
 8. The method of claim 6, wherein the gas is substantiallyfree of oxygen.
 9. The method of claim 6, wherein actuating the impacttool further comprises pumping, along with the gas, additional one ormore components selected from a lubricant, a friction reducer, a foam,oil, a mist, drilling mud, and water.
 10. The method of claim 1, furthercomprising rotating the drill bit while actuating the impact tool. 11.The method of claim 10, wherein rotating the drill bit further comprisesoperating a positive displacement motor which rotates the drill bit inresponse to fluid flow through the coiled tubing.
 12. The method ofclaim 10, wherein rotating the drill bit further comprises operating aturbine which rotates the drill bit in response to fluid flow throughthe coiled tubing.
 13. The method of claim 1, wherein actuating theimpact tool is performed while the drill bit is not rotated by a motor.14. The method of claim 1, wherein actuating the impact tool furthercomprises pumping a compressible fluid through the coiled tubing to theimpact tool.
 15. The method of claim 1, wherein actuating the impacttool further comprises pumping an incompressible fluid through thecoiled tubing to the impact tool.
 16. A coiled tubing drilling systemfor drilling a subterranean wellbore, the system comprising: coiledtubing; a drill bit; and an impact tool which delivers impacts to thedrill bit.
 17. The system of claim 16, wherein the drill bit rotateswhile the impact tool delivers the impacts to the drill bit.
 18. Thesystem of claim 16, further comprising a positive displacement motorwhich rotates the drill bit in response to fluid flow through the coiledtubing.
 19. The system of claim 16, further comprising a turbine whichrotates the drill bit in response to fluid flow through the coiledtubing.
 20. The system of claim 16, wherein the impact tool delivers theimpacts to the drill bit while the drill bit is not rotated by a motor.21. The system of claim 16, wherein the impact tool actuates in responseto a compressible fluid flowed through the coiled tubing to the impacttool.
 22. The system of claim 16, wherein the impact tool actuates inresponse to an incompressible fluid flowed through the coiled tubing tothe impact tool.
 23. The system of claim 16, wherein the impact toolcomprises a fluid hammer.
 24. The system of claim 16, wherein the impacttool comprises a pneumatic hammer.
 25. The system of claim 16, furthercomprising a shock absorber interconnected between the coiled tubing andthe impact tool.
 26. The system of claim 16, wherein the impact toolactuates in response to a liquid flowed through the coiled tubing to theimpact tool.
 27. The system of claim 16, wherein the impact toolactuates in response to a gas flowed through the coiled tubing to theimpact tool.
 28. The system of claim 27, wherein the gas comprisesnitrogen.
 29. The system of claim 27, wherein the gas is substantiallyfree of oxygen.
 30. The system of claim 27, wherein the impact toolactuates in response to, along with the gas, additional one or morecomponents selected from a lubricant, a friction reducer, a foam, oil, amist, drilling mud, and water, flowed through the coiled tubing to theimpact tool.